1916
E.
A. GOODHUE A N D H.
L. DUNLAP
Vol. 50
MINESAND METALLURGY, UNIVERITY MISSOURI]
[CONTRIBUTION FROM THE SCHOOL OF
OF
THE CATALYTIC ACTION OF NEUTRAL SALTS. THE EFFECT OF NORMAL ALKALI SULFATES ON ALKALI ACID SULFATES IN THE KETONIC SPLITTING OF ETHYL ACETOACETATE BY E. A. GOODHUE AND H. L. DUNLAP RECEIVED FSBRUARY 2, 1928
PUBLISHED JULY 6, 1928
I n this work the action of normal potassium and sodium sulfates has been investigated with two concentrations of their corresponding acid salts. The compound used for studying this effect is ethyl acetoacetate, which gives carbon dioxide upon its ketonic splitting in an acid solution, thus serving as a means for carefully following the course of the reaction. Also, this reaction is irreversible, as one of the products of the reaction is removed as a gas.
7-41
Fig. 1.
Biirki' used ethyl acetoacetate in his study of the hydrolysis reactions with sulfuric, hydrochloric and nitric acids and found that this ester was completely decomposed above 40'. The advantage in using this ester Burki, Helv. Chim. Acta, 1, 231 (1918).
:ruiy, 1928
KETONIC HYDROLYSIS OF E T H Y L ACETOACETATE
1917
is that the carbon dioxide evolved can be easily measured to follow the course of the reaction over a long period of time. The classical method2 of halting the reaction, if this is possible, and determining by titration the amount of ester hydrolyzed a t intervals, is subject to considerable error.
Experimental Part Materials.-The best grade of ethyl acetoacetate was redistilled under reduced pressure and the middle half of the distillate used. This was stored in amber colored bottles, each containing enough for a few determinations, in order not to expose the ester to air over too long a period. Plate The ethyl alcohol was dehydrated Glass over lime and anhydrous copper sulfate in the usual manner. The best grades of sodium and potassium sulfates and acid sulfates were each recrystallized from water several times, dried to constant ulted weight and analyzed for their sulfate content. The various stock soluItions of these salts were analyzed for Itheir sulfate content to make sure ,that all solutions were of known conicentrations. Aliquot parts of these !stock solutions were taken for dilu.tion to their required normalities. Apparatus.-T he a p p a r a t u s used in the work was developed by conDr. C. E. Boord and H. I,. Dunlap emei BOX .inan unpublished work on the study 1of alkali and alkaline earth chlorides with hydrochloric acid on the hydrolysis of this same ester. The thermostat was electrically heated and the temperature controlled to a tenth of a degree. The flasks were made specially for this work, having a capacity of two hundred cc. and with necks five inches in length. These were connected to a condenser (Fig. 1) by means of a two-holed rubber stopper, one for the condenser and the other for the stiff platinum wire which held the vial Fig. 2.-Gas measuring apparatus. containing the ester. The flask and condenser were firmly fastened to a frame which was suspended at the top, the lower part being connected to a pivoted arm from a pulley. In operation, this gave the flask a circular motion in the bath and thus agitated its contents. The neck of the flask extended three inches above the thermostat liquid and thus permitted the watching of the
/
Ostwald, J . prakt. Chem., 28, 449 (1883).
1918
E. A . GOODHUE AND H. I,. DUNLAP
VOl. 50
vial before its release. The side arm a t the top of the condenser permitted the adjusting of the pressure within the apparatus before tripping the ester into the solution for starting the reaction. The gas measuring apparatus (Fig. 2) is a modified Blier-White chain of bulbs type. A three-way manifold connects all compartments of the condenser and leveling bulbs. These gas measuring compartments were all carefully calibrated and the volume of gas a t any time could be read to one-tenth of a cc. The whole gas train was immersed in a water-filled box which had two opposite sides of glass. The temperature of the surrounding water was recorded with each reading for correcting the volume of the gas to standard conditions. Two sets of flasks were used in the thermostat, thus permitting of two determinations a t the same time. Readings were taken a t five-minute intervals.
600
500
400
c3
0
0-
2
300
-
i
> 200
100
0
50
100 150 200 Time in minutes. Fig. 3.-Hydrolysis ol N / 2 ester a t 90".
Experimental Procedure.-The desired concentration of salts was placed in the flasks along with one cc. of alcohol and water to make 46.8 cc. and when the ester (3.2527 g.) was introduced, this m$de 50 cc. of a half molar solution of ester. The capped vials containing the ester were held in place until the temperature of the flask and contents became that of the bath. After adjusting the measuring bulbs and starting agitation, the outside connection was closed, the vial dropped and the zero reading taken. As soon as 50 cc. of gas is collected in the burets, this is simply transferred to one of the 50-cc. bulbs. Checks were run in all cases with an allowable variation of three-fourths of one per cent. Vapor pressure corrections were made in all cases as that of pure water, which is in slight error but it is the same for all determinations.
July, 1928
KETONIC HYDROLYSIS OF E T H Y L ACETOACETATE
1919
”She volume of carbon dioxide was reduced to standard conditions and graphs were plotted for the five minute intervals. The data are condensed in Tables I to VII. The reaction constant is calculated according t o the formula where V, represents the corrected volume of carbon dioxide collected in time “t” and 560.3 is the volume of the gas which could be obtained by complete decomposition of the ester. The third column gives the various values for “k,” the constant for a first order reaction.
0.4 N HaSOi
-s
0.2 N HzSOt
X
c 3 .1
,
l
x+ I ‘0 3 0 3 J X
0.4 N NaHSO4
*Cc
0.4 N KHSO4
0.2 N 0.2 N 0.4 N 0.4 N I
NaHSO4 KHSOi NaHSOi-N NagSOa KHSO4-N KzSOd
0.2 N NaHSO4-N NazSOi 0.2 N KHSOi-N KzSOi
3
X i
N NazS04-KzSOi Hz0
3
0
50 Fig. 4.-Reaction
100 150 Time in minutes.
200
constants for hydrolysis of esters a t 90”.
:Data obtained with hydrolysis of the ester a t 90’ are shown graphically in Fig. 3 and the variation of the velocity constants with time is shown in Fig. 4. Similar curves are obtainable a t other temperatures. Discussion of Data.-It might be expected in the hydrolysis of the ester with pure acid that the reaction constant would increase with time as the more active hydrogen would be affected by the increasing concentration of the alcohol and acetone from the decomposition of the ester.
1920
E . A. GOODHUE AND H.L.
Vol. 50
DUNLAP
TABLE I HYDROLYSIS OF -v/2 At 80' with 0.2 N H604 0 . 4 h' HzSOi COa k X 103 Cot k X 10'
Time, min.
25 50 100 150 200
94.0 179.1 311.0 401.9 461.0
Time, mu.
COz
20 40 60 80 100
191.3 318.4 404.5 460.6 496.2
31.90 33.45 35.17 36.56 37.57
173.6 309.0 466.7 530.8 561.0
ETHYL ACETOACETATE
310.1 455.7 522.5 555.8
,..
min.
64.42 69.65 77.71 85.24
17.51 18.22 19.52 26.19
...
At 90' with 0 . 2 N H6Oa 0.4 N HzSOa Cot k X 108 COz k X loa
10 30 50 70 90
75.7 213.2 316.6 395.9 454.7
Time, min.
COz
...
At 9 5 ' with 0 . 2 N HzS04 0 . 4 N HzSOs k X 10' COa k X 10'
9.069 9.119 9.264 9.371 9.417
Time,
50 100 200 300 400
6.304 6.932 7.231 7.607 8.053
142.1 358.1 478.8 540.3
...
12.70 14.75 16.74 20.68
...
At 95' with N NazSO4 Cot k X 10'
Water alone k X 10'
20.9 0.333 24.4 0.387 39.2 ,315 46.9 .380 72.2 .300 85.0 .357 100.6 ,287 114.2 .330 125.9 ,276 139.9 ,314
TABLE11 NEUTRAL SALTEFFECT ON ACIDSULFATE IN HYDROLYSIS OF N/2 ETHYL ACETOACETATG Time, min.
25 50 100
150 200
0 . 2 N KHSO, COz k X 101
24.1 0.764 48.1 .780 93.6 .794 133.6 .796 172.5 .798
At 80" with 0 . 2 N KHSOi N KzSOa COz k X 108
11.8 0.370 23.0 .364 44.3 ,358 ,364 66.3 ,365 86.5
0 . 2 N NaHSO4 COz k X 10s
0 . 2 N NaHSOa N NazSOi Con k X 10'
27.3 0.868 54.6 .890 105.2 .903 150.5 .906 191.7 .909
12.5 0.395 .403 25.4 .410 51.0 .420 75.6 ,421 98.9
0 . 4 N NaHSOa Con k X l o 3
0 . 4 N NaHSOt N NazSO4 COz k X 108
At 80' with
0 . 4 N KHSOi
Time, min.
25 50
100 150 200
0 . 4 N RHSOi COS k X 10'
37.0 74.1 141.5 200.3 250.0
1.195 1.232 1.264 1.278 1.285
N KZSoi k X 10:
COa
17.6 0.554 35.5 .569 .573 69.2 100.9 .574 132.6 .586
1.434 1.485 1.521 1.538 1.555
20.7 0.657 41.7 .672 82.7 ,694 121.6 .708 .721 158.4
At 90' with 0 . 2 N KHSOd N K&O4 0 . 2 N NaHSOi COI k X 10: COI k X 10'
0 . 2 N NaHSOa
44.4 88.1 165.6 230.8 286.5
TABLEIV Time,
min.
0.2 N KHSO4 COS k X 101
22.4 0.709 42.2 1.360 81.6 1.367 42.5 .685 100 150.4 1.357 80.4 .673 150 209.0 1.358 115.0 ,665 200 149.1 260.7 1.359 ,667 Extrapolated from graphs. 25
50
N NazSO4 k X 10'
COz
49.8 1.617 24.5 0.777 94.6 1.606 47.0 .761 171.9 1.591 90.4 .764 130.5 ,767 237.3 1.595 (292.8)" (1.605)" (167.3)' (.770)"
July, 1928
TABLEV NEUTRAL SALT EFFECT ON ACIDSULFATE IN HYDROLYSIS OF N/2 Time, min.
1921
KETONIC HYDROLYSIS OF ETHYL ACSTOACETA'I'E
0 . 4 N KHSOI COz k X 108
ETHYL ACETOACETATE
At 90' with 0 . 4 N KHSO4 N KZSOI 0 . 4 N NaHSOk Con k X 10' Con k X 10'
1.071 1.078 1.089 1.097 1.112
65.0 2.142 33.5 25 50 123.6 2.164 65.4 100 222.6 2.198 124.3 176.7 150 299.7 2.210 200 359.2 2.225 225.0 " Extrapolated from graphs.
78.8 148.0 260.4 345.6 (405.3)'
0 . 4 N NaHSOd N NazSOi COz k X 103
2.633 37.3 1.197 74.1 1.230 2.664 141.3 1.262 2.714 2.777 202.1 1.295 (2.791)" (256.8)" (1.331)"
TABLEVI Time, min.
0 . 2 N KHSOi k X 193
COz
At 95' with 0 . 2 N KHSOc N KzSOc 0 , 2 N NaHSOc Con k X 108 COz k X 108
32.8 1.048 25 55.8 1.822 52.8 0.963 50 103.0 1.764 100 181.3 1.698 101.9 .872 139.0 .826 150 243.8 1.654 200 (296.4)' (1.634)' (173.0)' ( ,809)" Extrapolated from graphs.
62.9 116.1 199.5 264.9 316.0
2.068 2.017 1.912
1.853 1.803
0 2 N YaHSOc N NazSO4 Cor k X 108
34.9 63.5 111.2 152.5 (189.0)"
1.117 1.045 0.961 .919 ( .894)"
TABLEVI1 Time, am,
0 . 4 N KHSO4 COI k X 101
At 95' with 0 . 4 N KHSO, N Kzso4 0 . 4 N NaHSOd COa k X 10' CO1 k X 10:
46.5 82.7 2.774 50 148.2 2.668 83.1 100 250.6 2.575 147.5 150 322.8 2.485 202.2 200 (379.2)' (2.455)' 248.1 " Extrapolated from graphs. 25
80
90
95
Concn.
0 . 2 N KHSOi 0 . 2 N KHso4. N &So4 0 . 4 N KHSOi 0 . 4 N KHSO4, N &SO1 0 . 2 N KHSO4 0 . 2 N KHSO,, N &SO4 0 . 4 N KHSO4 0.4 N KHso4, N KeSO4
N
COz
"so4
k X 10'
48.3 1.566 1.505 95.5 3.250 1.394 171.6 3.178 89.5 1.512 1.328 284.5 3..078 161.6 1.478 1.295 359.3 2.968 220.3 1.446 1.270 (408.0)' (2.829)" (266.0)' (1.399)"
TABLE VI11 TIMERATIODATAFOR POTASSIUbl Temp., OC.
0 . 4 N NaHSO4
Time to produce 75 cc. o€ Cot, min.
172
50
109 46 93 28 58 0.2 N =so4 34 68 0 . 2 N KHSOI, N KzSO4 22 0 . 4 N KHSO4 0 . 4 N KHSOI, N 45 Average 0 . 2 N Average 0.4 N
SALTS
Ratio
0.465 .459 .495 .483 ,500 ,489 .487 ,477
Time to produce 150 cc. of COa, min.
...
... ...
99 202 63 124 79 166 50 102
Ratio
... ... ...
...
0.490
,508 ,476 .490 .483 * 499
1922
VOl. 50
CHARLES VINTON HART
The greater the concentration of the acid, the greater we should expect the variation of this reaction constant. Data in Table I show this to be true. The effect of the neutral salt on the rate of hydrolysis may be shown by calculating the ratio of the time required with the acid sulfate plus the neutral salt for producing 75 and 150 cc. of carbon dioxide, to the time required with the acid salt alone for producing the same quantity of carbon dioxide. In this manner the constituents in the solution will be the same a t the time of comparison. These calculations are given in Table VI11 for potassium salts and calculations for sodium salts give very similar results. Summary An apparatus has been devised for accurately measuring the velocity of reactions a t higher temperatures and over a long period of time with substances evolving a gas. The effects of normal sodium and potassium sulfates on their corresponding acid sulfates in the hydrolysis of ethyl acetoacetate have been studied a t the temperatures of 80°, 90' and 95'. ROLLA,MISSOURI [CONTRIBUTION FROM THE CHEMICAL LABORATORY OR STANFORD UNIVERSITY]
CARBONIC ACID AZIDES BY CHARLES VINTONHART^ RECEIVED FE~UAR 13,Y1928
PUBLISI
